<template>
  <div class="app-container">
    <h2 style="text-align: center;">发布新课程</h2>

    <el-steps :active="1" process-status="wait" align-center style="margin-bottom: 40px;">
      <el-step title="填写课程基本信息" />
      <el-step title="创建课程大纲" />
      <el-step title="提交审核" />
    </el-steps>

    <el-form label-width="120px">
      <el-form-item label="课程标题">
        <el-input v-model="courseInfo.title" placeholder=" 示例：机器学习项目课：从基础到搭建项目视频课程。专业名称注意大小写" />
      </el-form-item>

      <!-- 所属分类 TODO -->
      <el-form-item label="课程分类">
        <el-select
          v-model="courseInfo.subjectParentId"
          placeholder="一级分类"
          @change="subjectLevelOneChanged"
        >
          <el-option
            v-for="subject in subjectOneList"
            :key="subject.id"
            :label="subject.title"
            :value="subject.id"
          />
        </el-select>
        <!-- 二级分类 -->
        <el-select v-model="courseInfo.subjectId" placeholder="二级分类">
          <el-option
            v-for="subject in subjectTwoList"
            :key="subject.id"
            :label="subject.title"
            :value="subject.id"
          />
        </el-select>
      </el-form-item>
      <!-- 课程讲师 TODO -->
      <!-- 课程讲师 -->
      <el-form-item label="课程讲师">
        <el-select v-model="courseInfo.teacherId" placeholder="请选择">
          <el-option
            v-for="teacher in teacherList"
            :key="teacher.id"
            :label="teacher.name"
            :value="teacher.id"
          />
        </el-select>
      </el-form-item>

      <el-form-item label="总课时">
        <el-input-number
          :min="0"
          v-model="courseInfo.lessonNum"
          controls-position="right"
          placeholder="请填写课程的总课时数"
        />
      </el-form-item>

      <!-- 课程简介 TODO -->
      <!-- 课程简介-->
      <el-form-item label="课程简介">
        <tinymce :height="300" v-model="courseInfo.description" />
      </el-form-item>

      <!-- 课程封面 TODO -->
      <el-form-item label="课程封面">
        <el-upload
          :show-file-list="false"
          :on-success="handleAvatarSuccess"
          :before-upload="beforeAvatarUpload"
          :action="BASE_API+'/eduoss/fileoss'"
          class="avatar-uploader"
        >
          <img :src="courseInfo.cover" />
        </el-upload>
      </el-form-item>

      <el-form-item label="课程价格">
        <el-input-number
          :min="0"
          v-model="courseInfo.price"
          controls-position="right"
          placeholder="免费课程请设置为0元"
        />元
      </el-form-item>

      <el-form-item>
        <el-button :disabled="saveBtnDisabled" type="primary" @click="saveOrUpdate">保存并下一步</el-button>
      </el-form-item>
    </el-form>
  </div>
</template>

<script>
import course from "@/api/edu/course"
import subject from "@/api/edu/subject"
import Tinymce from "@/components/Tinymce"
export default {
  components: { Tinymce },
  data() {
    return {
      saveBtnDisabled: false,
      courseInfo: {
        title: "",
        subjectId: "", //二级分类id
        subjectParentId: "", //一级分类id
        teacherId: "",
        lessonNum: 0,
        description: "",
        cover: "/static/defaultCourseImg.jpg",
        price: 0
      },
      BASE_API: process.env.BASE_API, // 接口API地址
      teacherList: [], //封装所有讲师数据
      subjectOneList: [], //封装所有一级分类数据
      subjectTwoList: [] //封装所有二级分类数据
    };
  },
  created() {
    

    //若从第二步返回第一步, 则查询刚保存的信息,然后进行回显
    if(this.$route.params && this.$route.params.id) {
        let courseId = this.$route.params.id
        this.getCourseInfo(courseId)
    }else {
      //初始化所有讲师
      this.getAllTeacher()
      //初始化一级分类
      this.getOneSubject()
    }

  },
  methods: {
      //由第二步返回的回显方法
    getCourseInfo(courseId) {
        course.getCourseInfo(courseId)
            .then(response => {
                this.courseInfo = response.data.courseInfoVo
                //1 查询所有的分类, 包含一级和二级
                subject.getSubjectList()
                  .then(response=> {
                    //2 获取所有一级分类
                    this.subjectOneList = response.data.list
                    //3 把所有一级分类数组进行遍历, 比较当前courseInfo里面一级分类id和所有的一级分类id
                    for(let i=0; i<this.subjectOneList.length; i++) {
                      var oneSubject =  this.subjectOneList[i]
                      if(this.courseInfo.subjectParentId === oneSubject.id) {
                        this.subjectTwoList = oneSubject.children
                      }
                    }
                  })
                  this.getAllTeacher()
            })
    },
    //上传封面成功方法
    handleAvatarSuccess(response, file) {
      this.courseInfo.cover = response.data.url
    },
    //上传封面之前的方法
    beforeAvatarUpload(file) {
      const isJPG = file.type === "image/jpeg"
      const isLt2M = file.size / 1024 / 1024 < 2;

      if (!isJPG) {
        this.$message.error("上传头像图片只能是 JPG 格式!");
      }
      if (!isLt2M) {
        this.$message.error("上传头像图片大小不能超过 2MB!");
      }
      return isJPG && isLt2M;
    },
    //点击某个一级分类, 触发change, 显示对应二级分类
    subjectLevelOneChanged(value) {
      //固定写法value, 框架会得到该值 value就是一级分类id值
      //循环遍历进行判断, 取出一级分类id值取出二级分类
      for (let i = 0; i < this.subjectOneList.length; i++) {
        if (value === this.subjectOneList[i].id) {
          this.subjectTwoList = this.subjectOneList[i].children
        }
      }
      //当一级分类变化时, 清除二级分类的值.  (bug:不清除的话还会显示上次的数据)
      this.courseInfo.subjectId = ''
    },
    //查询所有的一级分类
    getOneSubject() {
      subject.getSubjectList().then(responese => {
        this.subjectOneList = responese.data.list
      })
    },
    //查询所有讲师
    getAllTeacher() {
      course.getListTeacher().then(response => {
        this.teacherList = response.data.items;
      })
    },
    addCourse() {
      course.addCourseInfo(this.courseInfo).then(response => {
          this.$message({
            type: "success",
            message: "添加课程信息成功!"
          })
          //跳转到下一步
          this.$router.push({
            path: "/course/chapter/" + response.data.courseId
          })
        })
    },
    updateCourse() {
      course.updateCourseInfo(this.courseInfo).then(response => {
          this.$message({
            type: "success",
            message: "修改课程信息成功!"
          })
          //跳转到下一步
          this.$router.push({
            path: "/course/chapter/" + this.courseInfo.id
          })
        })
    },
    saveOrUpdate(courseInfo) {
      //根据有无id判断修改还是新增
      if(!this.courseInfo.id) {
        this.addCourse()
      }else {
        this.updateCourse()
      }
      
    }
  }
}
</script>
<style scoped>
.tinymce-container {
  line-height: 29px;
}
</style>